Development and validation of the Standard method EN ISO 19020 - microbiology of the food chain - Horizontal method for the immunoenzymatic detection of staphylococcal enterotoxins in foodstuffs.

In the frame of the CEN Mandate M/381 from the European Commission to CEN (European Committee for Standardization), a method for the detection of staphylococcal enterotoxins in foodstuffs has been developed, validated and standardized. An extraction procedure based on dialysis concentration followed by an immuno-enzymatic detection has been defined. In addition, performance criteria (minimum values of sensitivity, specificity and level of detection) to be achieved by the commercially available immuno-enzymatic kits that could be used to detect staphylococcal enterotoxins in food matrices, were developed. A 2-stage validation study was conducted: The first stage aimed at selecting the commercial kits to be included in the second stage, which consisted in an interlaboratory study, using eight matrices covering five food categories (ready-to-eat food, meat products, milk products, dessert and fish). Results showed that two detection kits included in the study met the pre-defined performance criteria. The implementation of dialysis concentration step increased significantly the sensitivity of the method. The method developed allowed to achieve the Benchmark Dose lower limit (BMD10) estimated at 6.1 ng. In 2019, finally, the European Commission recognized this standard as the European Union reference method for the detection of staphylococcal enterotoxins in food.

Intra-laboratory validation of the Ridascreen® SET Total kit for detecting staphylococcal enterotoxins SEA to SEE in cheese.

AIM: To determine the performance of the Ridascreen® SET Total kit, after sample extraction and concentration by dialysis, with regard to its use in official controls for staphylococcal enterotoxins under European Regulation (EC) No. 2073/2005 modified. This study was conducted on naturally contaminated cheese samples and compared with the results of the previously validated Vidas® SET2 kit. METHODS AND RESULTS: The effectiveness of the Ridascreen® SET Total kit on naturally contaminated cheeses was compared to that of the Vidas® SET2 kit by applying the EN ISO 16140 standard. Sensitivity and specificity were also compared using spiked buffer solutions and cheese samples with SEA to SEE toxins. CONCLUSIONS: This study showed that the Ridascreen® SET Total kit is as effective as the Vidas® SET2 kit. SIGNIFICANCE AND IMPACT OF THE STUDY: The Ridascreen® SET Total kit was found to specifically detect SEA to SEE in cheeses. The Ridascreen® SET Total can therefore be used to check the staphylococcal enterotoxin content and ensure consumer protection.

First evidence of a food poisoning outbreak due to staphylococcal enterotoxin type E, France, 2009.

At the end of 2009, six food poisoning outbreaks caused by staphylococci were reported in France. Soft cheese made from unpasteurized milk was found to be the common source of the outbreaks. Staphylococcal enterotoxin type E was identified and quantified in the cheese using both official and confirmatory methods of the European Union Reference Laboratory (EU-RL). To our knowledge, this is the first report of food poisoning outbreaks caused by staphylococcal enterotoxin type E in France.

Intralaboratory validation according to the EN ISO 16 140 Standard of the Vidas SET2 detection kit for use in official controls of staphylococcal enterotoxins in milk products.

AIM: Immunological tools used to detect staphylococcal enterotoxins (SEs) in foods are numerous. The aim of this study was to evaluate, on naturally contaminated milk product samples, the performance of the Vidas SET2, in comparison to the Transia plate SET. METHODS AND RESULTS: The Vidas SET2 was compared with the Transia plate SET on supernatants of Staphylococcus aureus isolates and on naturally contaminated milk products. It is noteworthy that when using IgG rabbit treatment, both kits can be considered as equivalent to detect enterotoxins in naturally contaminated milk products. CONCLUSIONS: This study demonstrated that the Vidas SET2 performance is similar to that of Transia plate SET kit, when a rabbit IgG treatment step is used before detection step. This additional treatment significantly decreased, from 42% to 8%, the rate of positive deviations observed using the Transia plate SET detection kit. SIGNIFICANCE AND IMPACT OF THE STUDY: The Vidas SET2 was clearly found as more specific, when no preliminary rabbit IgG treatment was used, and which results in a better workflow when a large number of samples have to be analysed within a few days. Considering the results obtained, the Vidas SET2 detection kit can be used to assess the safety of milk products for SEs.